U.S. patent number 10,054,483 [Application Number 15/610,998] was granted by the patent office on 2018-08-21 for micromirror spectrophotometer assembly.
This patent grant is currently assigned to WESTCO SCIENTIFIC INSTRUMENTS, INC. The grantee listed for this patent is WESTCO SCIENTIFIC INSTRUMENTS, INC. Invention is credited to John Coates, David Naranjo, Jerome J. Workman, Jr..
United States Patent |
10,054,483 |
Workman, Jr. , et
al. |
August 21, 2018 |
Micromirror spectrophotometer assembly
Abstract
Aspects of a micromirror spectrophotometer assembly are
described. In one example case, an instrument includes a
diffraction grating to disperse broadband light over a range of
wavelengths, a detector, a digital micromirror device (DMD)
configured to scan through and reflect at least a portion of the
range of wavelengths toward the detector, and a base platform
having a number of integrally formed assembly mounts. The assembly
mounts are formed to align and secure the diffraction grating, the
detector, the DMD, and other optical components of the instrument
in a predetermined arrangement. The instrument can also include a
reference paddle having a reference material for calibration of the
instrument, and a rotatable sample tray to rotate a sample placed
on the sample tray for measurement.
Inventors: |
Workman, Jr.; Jerome J.
(Marlborough, MA), Coates; John (Newtown, CT), Naranjo;
David (Dracut, MA) |
Applicant: |
Name |
City |
State |
Country |
Type |
WESTCO SCIENTIFIC INSTRUMENTS, INC |
Brookfield |
CT |
US |
|
|
Assignee: |
WESTCO SCIENTIFIC INSTRUMENTS,
INC (Brookfield, CT)
|
Family
ID: |
62492496 |
Appl.
No.: |
15/610,998 |
Filed: |
June 1, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G01J
3/021 (20130101); G01J 3/28 (20130101); G01J
3/18 (20130101); G01J 3/0297 (20130101); G01J
3/0202 (20130101); G01J 3/0291 (20130101); G01J
3/0229 (20130101); G01J 3/0262 (20130101); G01J
2003/2866 (20130101) |
Current International
Class: |
G01J
3/28 (20060101); G01J 3/02 (20060101); G01J
3/18 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Nur; Abdullahi
Attorney, Agent or Firm: Thomas | Horstemeyer, LLP Crain; N
Andrew Perilla; Jason M.
Claims
At least the following is claimed:
1. An instrument, comprising: a diffraction grating to disperse
broadband light over a range of wavelengths; a detector; a digital
micromirror device (DMD) configured to scan through and reflect at
least a portion of the range of wavelengths toward the detector;
and a plurality of assembly mounts integrally formed as a base
platform to align and secure the diffraction grating, the detector,
the DMD, and a plurality of optical components of the instrument in
a predetermined arrangement, wherein: the plurality of the assembly
mounts comprise a plurality of integral seats to align and secure
the plurality of optical components of the instrument in a
predetermined arrangement relative to each other and the
diffraction grating, the detector, and the DMD; and the plurality
of integral seats are individually separated by a predetermined
spacing along at least one optical pathway in the instrument.
2. The instrument of claim 1, wherein at least one of the plurality
of assembly mounts comprises: a first integral seat formed for a
first optical component of a focusing optics assembly; and a second
integral seat for a second optical component of the focusing optics
assembly, the first integral seat and the second integral seat
being separated by a predetermined spacing along an optical pathway
that extends along the at least one of the plurality of assembly
mounts.
3. The instrument of claim 1, wherein: a first of the plurality of
assembly mounts is aligned along a first optical pathway in the
instrument; a second of the plurality of assembly mounts is aligned
along a second optical pathway parallel to the first optical
pathway in the instrument; and a third of the plurality of assembly
mounts is aligned along a third optical pathway at an angle with
respect to at least one of the first optical pathway and the second
optical pathway in the instrument.
4. The instrument of claim 3, wherein: the plurality of optical
components are aligned and secured in the first, second, and third
of the plurality of assembly mounts; and an assembly mount cover is
secured over the first, second, and third of the plurality of
assembly mounts.
5. The instrument of claim 3, wherein a fourth of the plurality of
assembly mounts is aligned at one end of the first optical pathway
to secure a light source and an entrance optics assembly of the
instrument.
6. The instrument of claim 5, wherein a fifth of the plurality of
assembly mounts is positioned about an intersection of the first
optical pathway and the second optical pathway to secure the
diffraction grating.
7. The instrument of claim 6, wherein: a sixth of the plurality of
assembly mounts is positioned about an intersection of the second
optical pathway and the third optical pathway to secure the DMD;
and the sixth of the plurality of assembly mounts includes a number
of baffles integral to the base platform.
8. The instrument of claim 1, wherein the base platform is
continuously formed from a single material using an additive
manufacturing process.
9. The instrument of claim 1, further comprising: a motor
comprising a shaft; and a reference paddle mechanically coupled to
the shaft of the motor, wherein: the reference paddle includes a
reference material for calibration of the instrument; and the motor
is configured to rotate the reference paddle to cover a sample
window of the instrument for calibration of the instrument.
10. The instrument of claim 1, further comprising: a motor
comprising a shaft that extends through a sample platform 30 of the
instrument; and a sample tray mechanically coupled to the shaft of
the motor, wherein the motor is configured to rotate a sample
placed on the sample tray for measurement.
11. A method of assembly for an instrument, comprising: forming a
base platform comprising a plurality of integral assembly mounts;
securing a diffraction grating in a first of the plurality of
integral assembly mounts; securing a digital micromirror device
(DMD) in a second of the plurality of integral assembly mounts;
securing a detector in a third of the plurality of integral
assembly mounts; and seating at least one optical component of the
instrument in a fourth of the plurality of integral assembly
mounts, wherein the diffraction grating, the DMD, the detector, and
the at least one optical component are aligned and secured in a
predetermined arrangement based on relative positions of the
plurality of integral assembly mounts of the base platform.
12. The method of assembly for the instrument of claim 11, further
comprising installing a cover over the base platform.
13. The method of assembly for the instrument of claim 11, further
comprising installing an assembly mount cover over the fourth of
the plurality of integral assembly mounts.
14. The method of assembly for the instrument of claim 11, wherein:
the first of the plurality of integral assembly mounts is aligned
along a first optical pathway in the instrument; and the second of
the plurality of integral assembly mounts is aligned along a second
optical pathway parallel to the first optical pathway in the
instrument.
15. The method of assembly for the instrument of claim 11, wherein
forming the base platform comprises forming the base platform using
an additive manufacturing process.
16. An instrument, comprising: a diffraction grating to disperse
broadband light over a range of wavelengths; a detector; a digital
micromirror device (DMD) configured to scan through and reflect at
least a portion of the range of wavelengths toward the detector;
and a plurality of assembly mounts integrally formed as a base
platform to align and secure the diffraction grating, the detector,
the DMD, and at least one optical component of the instrument in a
predetermined arrangement.
17. The instrument of claim 16, wherein at least one of the
plurality of the assembly mounts comprises a seat to align and
secure the at least one optical component of the instrument in a
predetermined arrangement relative to the diffraction grating, the
detector, and the DMD.
18. The instrument of claim 17, wherein the at least one of the
plurality of the assembly mounts comprises: a first integral seat
formed for a first optical component of an optics assembly; and a
second integral seat for a second optical component of the optics
assembly, the first integral seat and the second integral seat
being separated by a predetermined spacing along an optical pathway
in the instrument.
19. The instrument of claim 16, wherein the base platform is
continuously formed from a single material using an additive
manufacturing process.
20. The instrument of claim 1, further comprising: a motor
comprising a shaft; and a reference paddle mechanically coupled to
the shaft of the motor, wherein: the reference paddle includes a
reference material for calibration of the instrument; and the motor
is configured to rotate the reference paddle to cover a sample
window of the instrument for calibration of the instrument.
Description
BACKGROUND
Spectrophotometers can be used to measure the intensity of light as
a function of its wavelength over a spectral range of light (e.g.,
the spectral bandwidth of the spectrophotometer). For a
spectrophotometer, important aspects of measurements include the
absorption, transmittance, and reflectance of light by samples, for
example, measured as a percentage or other gauge or metric.
Spectrophotometers are often used to identify or determine the
quality or quantity of solutions and solids based on the
transmittance and reflectance characteristics of those samples.
BRIEF DESCRIPTION OF THE DRAWINGS
Aspects of the embodiments described herein can be better
understood with reference to the following drawings. The elements
in the drawings are not necessarily drawn to scale, with emphasis
instead being placed upon clearly illustrating the principles of
the embodiments. Additionally, certain dimensions or positionings
can be exaggerated to help visually convey certain principles. In
the drawings, similar reference numerals between figures designate
like or corresponding, but not necessarily the same, elements.
FIG. 1 illustrates an example spectrophotometer according to an
embodiment described herein.
FIG. 2 illustrates a representative block diagram of the example
spectrophotometer shown in FIG. 1 according to an embodiment
described herein.
FIG. 3 illustrates a top-down view of a base platform of the
measurement unit in the example spectrophotometer shown in FIG. 1
according to an embodiment described herein.
FIG. 4 illustrates a perspective view of the base platform of the
measurement unit in the example spectrophotometer shown in FIG. 1
according to an embodiment described herein.
FIG. 5 illustrates a perspective view of the base platform,
assembly mount cover of the base platform, and cover of the
measurement unit in the example spectrophotometer shown in FIG. 1
according to an embodiment described herein.
FIGS. 6A and 6B, respectively, illustrate top and bottom views of a
sample platform of the example spectrophotometer shown in FIG. 1
according to an embodiment described herein.
FIG. 7 illustrates a sample tray of the example spectrophotometer
shown in FIG. 1 according to an embodiment described herein.
FIG. 8 illustrates an example schematic block diagram of processing
circuitry which can be employed in the spectrophotometer shown in
FIG. 1 according to an embodiment described herein.
DETAILED DESCRIPTION
According to aspects of the embodiments described herein, Digital
Light Processing (DLP) Digital Micromirror Device (DMD) (DLP-DMD)
technology is incorporated into a low-cost, commercial production
spectrophotometer using an integral, singular-unit base platform or
chassis assembly. The base platform or chassis assembly includes a
number of optical assembly mounts. The base platform assembly
facilitates the assembly of optics in a predetermined, pre-aligned
spectrophotometer configuration for taking spectral measurements of
various samples, including natural and synthetic food and
agricultural products, among others. Features of the embodiments
include a simple-to-use, pre-aligned optical and electronic base
platform assembly, an automatic reference reflector, and a rotating
sample tray. The embodiments can also rely upon spectral region
measurement stitching, spectral and calibration transfer between
instruments, and the alignment of spectra with specialized
wavelength standards, photometric standards, and lineshape
correction methods.
In one example described below, an instrument includes a
diffraction grating to disperse broadband light over a range of
wavelengths, a detector, a digital micromirror device (DMD)
configured to scan through and reflect at least a portion of the
range of wavelengths toward the detector, and a base platform
having a number of integrally formed assembly mounts. The assembly
mounts are formed to align and secure the diffraction grating, the
detector, the DMD, and other optical components of the instrument
in a predetermined arrangement. The instrument can also include a
reference paddle having a reference material for calibration of the
instrument, and a rotatable sample tray to rotate a sample placed
on the sample tray for measurement.
Turning to the drawings, FIG. 1 illustrates an example
spectrophotometer 10 according to an embodiment described herein.
Before continuing with a description of the spectrophotometer 10,
it is noted that FIG. 1 is provided as a representative example for
discussion. The example shown in FIG. 1 is not necessarily drawn to
scale, does not exhaustively illustrate every part, piece, or
component of the spectrophotometer 10, and is not intended to be
limiting of the embodiments. Other arrangements of similar,
additional, or fewer components can be used to achieve any number
of the advantages described herein.
Among other components, the spectrophotometer 10 includes an
enclosure 20, a sample platform 30 positioned at a top side of the
enclosure 20, a power supply module 40, a computer control module
50, a support chassis 60, and a DLP-DMD measurement unit 100
("measurement unit 100"). The measurement unit 100 is secured by
the support chassis 60 within the enclosure 20.
The enclosure 20 can be embodied as any suitable case or enclosure,
formed from plastic, metal, rubber, other materials, and/or
combinations thereof, for enclosing and securing the components of
the spectrophotometer 10. Similarly, the support chassis 60 within
the enclosure 20 can be formed from plastic, metal, rubber, and
other materials suitable for supporting and securing the
measurement unit 100, the sample platform 30, and other components
of the spectrophotometer 10, such as a monitor, keyboard, mouse,
etc. Both the enclosure 20 and the support chassis 60 can be
embodied as a number of parts and/or pieces secured together using
any suitable means, such as mechanical interferences or joints,
mechanical fasteners (e.g., screws, rivets, pins, interlocks),
adhesives, etc.
At the top of the enclosure 20, the sample platform 30 includes a
sample window 32 as shown in FIG. 1. As discussed in further detail
below, samples for measurement by the spectrophotometer 10 can be
placed in a sample cup, for example, and placed over the sample
window 32 for measurement by the measurement unit 100 of the
spectrophotometer 10 and analysis by the computer control module
50.
The power supply module 40 can be embodied as any suitable power
supply (e.g., switch-mode, regulated, or other power supply) to
provide power to the computer control module 50, the measurement
unit 100, and other components of the spectrophotometer 10, such as
stepper and/or servo motors, solenoids, relays, and fans, among
other components. In that context, the power supply module 40 can
convert power from line voltage to lower voltage direct current
power suitable for components in the spectrophotometer 10.
The computer control module 50 can be embodied as one or more
circuits, processors, processing circuits, memory devices, or any
combination thereof configured to control components in the
spectrophotometer 10. For example, the computer control module 50
can be configured to capture, store, and analyze data captured by a
detector in the measurement unit 100, as described in further
detail below. The computer control module 50 can also be configured
to forward and/or display data to other computing or display
device(s), receive control instructions or feedback through I/O
interfaces (e.g., keyboards, keypads, touchpads, pointing devices)
of the spectrophotometer 10, and store and process various types of
data.
FIG. 2 illustrates a representative block diagram of the example
spectrophotometer 10 shown in FIG. 1 according to an embodiment
described herein. In FIG. 2, a number of components of the
measurement unit 100 are shown. Additionally, a representative
sample tray 102, sample tray drive motor 104, reference paddle 108,
and reference paddle actuator 110 are shown. In the example shown
in FIG. 2, the reference paddle 108 is positioned within the
enclosure 20, and the sample tray 102 is positioned outside the
enclosure 20. The representative sample tray 102, sample tray drive
motor 104, reference paddle 108, and reference paddle actuator 110
are described in further detail below with reference to FIGS. 6A
and 6B.
Among other components, the measurement unit 100 includes a light
source assembly 120, an optical focusing assembly 130, a
diffraction grating 140, another optical focusing assembly 150, a
digital micromirror device (DMD) 160, an optical collimating
assembly 170, and a detector 180. The light source assembly 120
includes a light source 122 and an entrance optics assembly
124.
The entrance optics assembly 124 is aligned with an entrance
opening 126 in a cover of the measurement unit 100. During
operation of the spectrophotometer 10, light from the light source
122 can travel along an optical pathway 200 in the light source
assembly 120, through the sample window 32, and illuminate a sample
placed on, in, or over the sample tray 102. Light reflected (and
not absorbed) off the sample can travel along an optical pathway
202, through the entrance optics assembly 124, and through the
entrance opening 126 in the cover of the measurement unit 100. The
cover of the measurement unit 100 is described in further detail
below with reference to FIG. 5.
In one embodiment, the light source 122 can include a halogen lamp
or light bulb, although any source of broadband light suitable for
the application can be relied upon among embodiments. The entrance
optics assembly 124 can include optical elements that collimate
light reflected off the sample, such as one or more spaced-apart
expander and/or plano-convex lenses or other elements, without
limitation. The entrance opening 126 can include a slit or other
opening though which at least a portion of the light reflected off
the sample can be passed through the cover of the measurement unit
100. In some cases, entrance opening 126 can be selectively covered
and/or uncovered by a mechanical or electrical shutter (e.g., a
liquid crystal, LCD, or similar device). The shutter can be
actuated and controlled by the computer control module 50, for
example, during various operations of the spectrophotometer 10,
such as during dark scans, calibration or reference scans, and live
scan operations, for example.
After passing through the entrance opening 126 along the optical
pathway 202, light reflected off the sample can pass through the
optical focusing assembly 130 to reach the diffraction grating 140.
The optical focusing assembly 130 can include one or more
spaced-apart lenses, such as the lenses 132 and 134 and the optical
filter 136 (e.g., optical bandwidth filter) shown in FIG. 2. As
described in further detail below with reference to FIGS. 3-5, the
lenses 132 and 134 and optical bandpass filter 136 can be secured
in an optical assembly mount of a base platform of the measurement
unit 100.
The diffraction grating 140 can be embodied as a grating selected
to disperse the light reflected off the sample into a range of
wavelengths of light. For example, the diffraction grating 140 can
disperse light over the ultra-violet (UV) to visible (VIS) range of
wavelengths. In another case, the diffraction grating 140 can
disperse light over the near-infrared (NIR) to infrared (IR) range
of wavelengths. In various embodiments, the diffraction grating 140
can be selected to disperse light over any desired range of
wavelengths.
The diffraction grating 140 can be embodied as substrates of
various sizes with parallel grooves replicated on their surfaces,
as would be appreciated in the art. The diffraction grating 140
disperses the light reflected off the sample by spatially
separating it according to wavelength. Various methods of
manufacture of diffraction gratings are known in the field, and the
diffraction grating 140 can be manufactured using any known method,
such as by replication from master gratings, interferometric
control, holographic generation, ion etching, or lithography, for
example. The diffraction grating 140 can also include a coating of
reflective material over the grooves, to reflect light. The
diffraction grating 140 can be sourced from any manufacturer of
diffraction gratings, such as Optometrics Corporation of Littleton,
Mass., Grating Works of Acton, Mass., or Richardson Gratings.TM. of
Rochester, N.Y., for example, among others.
After being dispersed by the diffraction grating 140, the light
reflected off the sample can travel through the optical focusing
assembly 150 along the optical pathway 204 to reach the DMD 160.
The optical focusing assembly 150 can include one or more
spaced-apart lenses, such as the lenses 152 and 154 shown in FIG.
2. As described in further detail below with reference to FIGS. 3
and 4, the lenses 152 and 154 can be secured in an optical assembly
mount of the base platform of the measurement unit 100.
The DMD 160 can be embodied as an array of hundreds of thousands to
millions of micromirrors. The micromirrors of the DMD 160 can be
controlled, respectively, by the computer control module 50 (and/or
additional electronic components) to scan through and reflect at
least a portion of the dispersed wavelengths of light from the
diffraction grating 140 along the optical pathway 206 toward the
detector 180. Using the DMD 160, one or more wavelengths or ranges
of wavelengths can be reflected toward the detector 180 for
measurement over time. Individual wavelengths or ranges of
wavelengths can be selected over time (e.g., scanned) by the
computer control module 50 by selectively turning columns of
micromirrors in the DMD 160 on or off, to reflect desired
wavelengths to the detector 180. The DMD 160 allows for the use of
a high-performance detector 180, while providing wavelength
selection agility and speed in the spectrophotometer 10. Further,
the DMD 160 allows for mechanical stability in the
spectrophotometer 10 because it is not necessary to pivot or rotate
the diffraction grating 140 as compared to conventional
techniques.
After being reflected by the DMD 160, the light reflected off the
sample can travel through the optical collimating assembly 170
along the optical pathway 206 to reach the detector 180. The
optical collimating assembly 170 can include one or more
spaced-apart lenses, such as the lenses 172, 174, and 176 shown in
FIG. 2. As described in further detail below with reference to
FIGS. 3 and 4, the lenses 172 and 174 can be secured in an optical
assembly mount of the base platform of the measurement unit
100.
The detector 180 is configured to measure the intensity of the
light reflected off the sample (or the fraction of the light
absorbed by the sample at specific wavelengths, i.e., the
absorbance of the sample). The detector 180 further converts the
light to one or more electrical signals for analysis by the
computer control module 50. In the computer control module 50, the
electrical signals can be converted (e.g., using one or more analog
to digital converters) to data values from which a quantitative
analysis of a variety of characteristics of the sample, including
constituent analysis, moisture content, protein content, fat
content, fiber content, amino acid content, taste, texture,
viscosity, etc., can be determined. The detector 180 can include
one or more charge-coupled device (CCD), indium gallium arsenide
(InGaAs), or other ultraviolet through infrared image or light
sensors that observe the reflection of light from the sample at one
or more points of illumination. The field of view of the detector
180 can be restricted based on the relative geometry and/or
placement of the lenses 172, 174, and 176 to maximize the
collection of energy while minimizing the light inclusion of stray
light.
FIG. 3 illustrates a top-down view and FIG. 4 illustrates a
perspective view of the base platform 300 of the measurement unit
100 in the example spectrophotometer 10 shown in FIG. 1. The
embodiment of the base platform 300 shown in FIGS. 3 and 4 is
provided as a representative example. In other cases, the base
platform 300 can include other arrangements (and numbers) of
assembly mounts and seats within the assembly mounts.
As shown in FIGS. 3 and 4, the base platform 300 includes a number
of assembly mounts which are described in further detail below. A
number of the assembly mounts are aligned along (and/or interfere
with) one or more of the optical pathways 200, 202, 204, and 206.
Some of the assembly mounts can be used to secure one or more
lenses, optical filters, and/or other components in a
predetermined, pre-aligned arrangement. Other assembly mounts can
be used to secure one or more gratings, such as the diffraction
grating 140, and electrical or optical-electrical components, such
as the DMD 160 and the detector 180.
In one aspect of the embodiments, the base platform 300 can be
formed as a single, integral unit. To that end, the base platform
300 can be formed using an additive manufacturing process. Additive
manufacturing processes include those processes by which
three-dimensional (3D) objects can be formed by adding
layer-upon-layer of the same material. Additive manufacturing
processes include many technologies including 3D printing, rapid
prototyping (RP), direct digital manufacturing (DDM), layered
manufacturing, and additive fabrication. The process can be
conducted using any suitable material, such as a plastic or polymer
(e.g., acrylonitrile butadiene styrene (ABS), nylon, plastic resin,
etc.), poly-foam, Delrin.RTM., metal, etc. In other approaches, the
base platform 300 can be formed using other manufacturing
processes, such as computer numerical control (CNC) machining
and/or tooling processes, where material is removed from a larger
workpiece.
During the additive manufacturing process, the assembly mounts of
the base platform 300 can be formed to include a number of seats to
secure one or more lenses, optical filters, and/or other components
of the measurement unit 100 in a predetermined, pre-aligned
arrangement. Starting with the base platform 300, the measurement
unit 100 of the spectrophotometer 10 can be assembled relatively
quickly and easily in a repeatable fashion. Specifically, each of
the lenses, optical filters, and/or other components of the
measurement unit 100 can be inserted and secured into a
corresponding seat in an assembly mount of the base platform
300.
Each of the lenses, optical filters, and/or other components of the
measurement unit 100 may take a different form, shape, and/or size.
Thus, the seats for each of the components can, similarly, take a
different form, shape, and/or size. In some cases, each of the
components will fit into one and only one seat (and possibly in
only one orientation) in the base platform 300. In that case, the
measurement unit 100 of the spectrophotometer 10 can be assembled
in only one way.
Referring between FIGS. 3 and 4, the base platform 300 includes the
assembly mounts 320, 330, 340, 350, 360, and 370, for securing the
light source assembly 120, the optical focusing assembly 130, the
diffraction grating 140, the optical focusing assembly 150, the DMD
160, and the optical collimating assembly 170 and detector 180,
respectively. As shown in FIG. 3, the assembly mounts 320, 330, and
340 are spaced along the optical pathways 200 and 202. The assembly
mounts 340, 350 and 360 are spaced along the optical pathway 204.
The assembly mounts 360, 370, and 380 are spaced along the optical
pathway 206.
To assemble the measurement unit 100, the light source 122 and the
entrance optics assembly 124 can be secured within the assembly
mount 320 by sliding them into openings within the assembly mount
320 and securing them in place using mechanical interferences or
joints, mechanical fasteners (e.g., screws, rivets, pins,
interlocks), adhesives, etc. Similarly, the diffraction grating 140
can be secured within the assembly mount 340 by sliding it into the
assembly mount 340 and securing it in place with any suitable
means. The DMD 160 can also be secured within or to the assembly
mount 360 by sliding it into the assembly mount 340 and securing it
in place with any suitable means. As shown in FIGS. 3 and 4, the
assembly mount 360 includes a number of baffles 362 and 364 to
mitigate or block stray light within the measurement unit 100.
The lenses 132 and 134 and the optical filter 136 of the optical
focusing assembly 130 can be placed and secured into the seats 332,
334, and 336 of the assembly mount 320. Similarly, the lenses 152
and 154 of the optical focusing assembly 150 can be placed and
secured into the seats 352 and 354 of the assembly mount 350. The
lenses 172, 174, and 176 of the optical collimating assembly 170
can also be placed and secured into the seats 372, 374, and 376 of
the assembly mount 370. The detector 180 can be placed and secured
into the seat 378 of the assembly mount 370.
The components (e.g., lenses, filters, mirrors, gratings,
detectors, etc.) of the measurement unit 100 can be secured into
the seats of the base platform 300 by being placed within and, in
some cases, held in place by mechanical contact, foam spacers,
adhesives, or other means. Further, after various components have
been seated into the seats 332, 334, 336, 352, 354, 372, 374, and
376 of the assembly mounts 330, 350, 360, and 370, the assembly
mounts 330, 350, 360 and 370 can be closed using one or more
assembly mount covers, such as the assembly mount cover 400 shown
in FIG. 4. The assembly mount cover 400 can include seats
corresponding in size and position with the seats 332, 334, 336,
352, 354, 372, 374, and 376 of the assembly mounts 330, 350, and
370.
One or more of the assembly mounts 330, 350, and 370 can include
holes (e.g., see reference 398 in FIG. 3), which can be threaded in
some cases. The assembly mount cover 400 can also include holes,
one of which is designated by reference 402 in FIG. 4. After
various components have been seated into the assembly mounts 330,
350, 360, and 370, the assembly mount cover 400 can be placed over
the assembly mounts 330, 350, and 370. Among other fasteners, a
mechanical fastener, such as a screw, can be passed through the
hole 402 of the assembly mount cover 400 and threaded into the hole
398 (see FIG. 3) of the assembly mount 350 for securing the
assembly mount cover 400 over the assembly mounts 330, 350, and
370.
In one example case, each of the seats 332, 334, 336, 352, 354,
372, 374, and 376 is formed to have a predetermined size (e.g.,
length, width, height, radius of curvature, etc.) for a particular
one of the components of the measurement unit 100. Further, the
placement of each of the components can be predetermined in a
particular spaced-apart arrangement defined by the base platform
300 with respect to one or more of the optical pathways 200, 202,
204, and 206. For example, as shown in FIG. 3, the seats 372 and
374 are spaced apart by the distance "A" along the optical pathway
206, and the seats 374 and 376 are spaced apart by the distance "B"
along the optical pathway 206. In other embodiments, any of the
seats shown in FIGS. 3 and 4 can be spaced-apart by other distances
depending upon the types and arrangements of the components of the
measurement unit 100.
Again, once the base platform 300 is formed, the measurement unit
100 can be assembled relatively quickly and easily as each of the
lenses, optical filters, and other components of the measurement
unit 100 can be inserted and secured into a corresponding assembly
mount and/or seat of the base platform 300. In some cases, each of
the components will fit into one and only one assembly mount and/or
seat (and possibly in only one orientation) in the base platform
300. In that case, the measurement unit 100 of the
spectrophotometer 10 can be assembled in only one way. As compared
to conventional techniques without the use of a base platform as
described herein, it can be relatively time consuming and difficult
to ensure that all the components of a spectrophotometer are
aligned properly.
The base platform 300 also includes number of standoffs 390-393 and
eyelets 394 and 395 as shown in FIG. 3. As described in further
detail below with reference to FIG. 5, a cover can be mounted over
the base platform 300, seated into and against the channel 396
along a length of the bottom edge of the base platform 300, and
secured against the top ends of the standoffs 390-393 using screws
or other mechanical fastening means. When the measurement unit 100
is fully assembled and the cover of the base platform 300 is
secured, the measurement unit 100 can be secured to the support
chassis 60 within the enclosure 20 of the spectrophotometer 10 as
shown in FIG. 1. The eyelets 394 and 395 can be used to pass wiring
assemblies, harnesses, etc. between the components inside the
measurement unit 100, the power supply module 40, and the computer
control module 50.
Before turning to FIG. 5, it is again noted that the base platform
300 illustrated in FIGS. 3 and 4 is provided as a representative
example. Other base platforms for other instruments can include
other numbers and arrangements of assembly mounts. In that sense,
other base platforms can include assembly mounts aligned along
optical pathways other than those shown in FIGS. 3 and 4. For
example, although the optical pathways 202 and 206 extend parallel
to each other, and the optical pathway 202 extends at an angle
.PHI. with respect to the optical pathway 204, assembly mounts can
be formed at other positions in a base platform for alignment to
other optical pathways at other angles with respect to each other
in any suitable manner.
FIG. 5 illustrates a perspective view of the base platform 300,
assembly mount cover 400 of the base platform 300, and cover 500 of
the measurement unit 100 in the example spectrophotometer 10 shown
in FIG. 1. As described above, the base platform 300 includes a
number of standoffs 390-393. After the assembly mount cover 400 is
secured to the base platform 300, the cover 500 can be mounted over
the base platform 300, seated into and against the channel 396
along a length of the bottom edge of the base platform 300, and
secured against the top ends of the standoffs 390-393 using screws
or other mechanical fastening means passed through holes 501-504 in
the cover 500. When the measurement unit 100 is fully assembled and
the cover 500 of the base platform 300 is secured, the measurement
unit 100 can be secured to the support chassis 60 within the
enclosure 20 of the spectrophotometer 10.
FIGS. 6A and 6B, respectively, illustrate top and bottom views of a
sample platform 30 of the example spectrophotometer 10 shown in
FIG. 1. As shown in FIG. 6A, the sample platform includes the
sample window 32. Light from the light source assembly 120 can pass
through the sample window 32 and exit the enclosure 20 of the
spectrophotometer 10 along optical pathway 200 (FIG. 2). As also
described in further detail below with reference to FIG. 7, light
that passes through the sample window 32 can illuminate a sample
placed on, in, or over the sample tray 102 above the sample window
32. Light reflected (and not absorbed) off the sample can travel
back through the sample window 32 and into the measurement unit
100.
Referring to FIG. 6B, a motor 600 is secured to the bottom side of
the sample platform 30. A stepper or servo motor 630 is also
secured to the bottom side of the sample platform 30. As described
in further detail below with reference to FIG. 7, the computer
control module 50 can also control the servo motor 630 to rotate a
sample tray 102 placed over the sample window 32 in the sample
platform 30.
A reference paddle 610 is mechanically secured to a shaft of the
motor 600. When assembled with the motor 600 to the sample platform
30, the reference paddle 610 occupies a recess 620 in the bottom of
the sample platform 30. The computer control module 50 can control
the motor 600 to rotate the reference paddle 610 between a first
position 622 in the recess 620 and a second position 624 in the
recess 620.
In the first position 622 shown in FIG. 6B, the reference paddle
610 covers the sample window 32. As such, it interferes with the
optical pathway 200 (FIG. 2). In the first position 622, light from
the light source assembly 120 falls upon and is reflected off of
the reference paddle 610 rather than passing through the sample
window 32. The reference paddle 610 includes a recessed area 612
for a reflective reference material. In one embodiment, the
recessed area 612 can be covered in gold plating reflective
reference material for calibration of the spectrophotometer 10. In
other embodiments, the recessed plating area 612 can be covered or
plated using other reference materials, such as
polytetrafluoroethylene (PTFE), teflon, reflective metal(s), or a
diffuse mirrored surface material, among others.
FIG. 7 illustrates the sample tray 102 of the example
spectrophotometer 10 shown in FIG. 1. The sample tray 102 is
mechanically coupled to a shaft of the stepper or servo motor 630
(FIG. 6B) through the sample platform 30, and the computer control
module 50 can also control the servo motor 630 to rotate the sample
tray 102. Thus, the sample tray 102 can be rotated at the direction
of the computer control module 50.
The sample tray 102 includes a sample cup adapter 700 mounted and
secured thereto. As shown in FIG. 7, the sample cup adapter 700 is
mounted to the sample tray 102 above the sample window 32. When a
sample for measurement is placed in or on the sample cup adapter
700, possibly in a sample cup or other fixture, it can be rotated.
In other words, sample cup adapter 700 can be rotated along with
the sample tray 102 using the stepper or servo motor 630. The
sample cup adapter 700 can be rotated at different (or variable)
speeds, for example, from a few degrees per second to about 180
degrees per second based on control provided by the computer
control module 50.
By rotating the sample during measurements taken by the
spectrophotometer 10, measurements can be taken in a more
representative and/or comprehensive manner because light can be
reflected (or absorbed) off the sample at different times or over
time from different positions or orientations of the sample.
In some embodiments, one or more aspects of spectral region
measurement stitching, spectral and calibration transfer between
instruments, and the alignment of spectra with specialized
wavelength standards, photometric standards, and lineshape
correction methods can be incorporated into the spectrophotometer
10. For example, the aspects described in any of U.S. patent
application Ser. No. 13/829,651, titled "SPECTROMETER SECONDARY
REFERENCE CALIBRATION"; U.S. patent application Ser. No.
14/600,454, titled "SPECTROMETER REFERENCE CALIBRATION"; U.S. Pat.
No. 9,404,799, titled "TANDEM DISPERSIVE RANGE MONOCHROMATOR"; or
U.S. patent application Ser. No. 15/416,552, titled "DATA BLENDING
MULITPLE DISPERSIVE RANGE MONOCHROMATOR" can be incorporated into
the spectrophotometer 10. The entire disclosures of each of U.S.
patent application Ser. No. 13/829,651; U.S. patent application
Ser. No. 14/600,454; U.S. Pat. No. 9,404,799; and U.S. patent
application Ser. No. 15/416,552, titled "DATA BLENDING MULITPLE
DISPERSIVE RANGE MONOCHROMATOR" are hereby incorporated herein by
reference.
FIG. 8 illustrates an example schematic block diagram of processing
circuitry which can be employed as the computer control module 50
in the spectrophotometer 10 shown in FIG. 1 according to an
embodiment described herein. The processing circuitry 800 can be
embodied, in part, using one or more elements of a general purpose
or specialized embedded computer. The processing circuitry 800
includes a processor 810, a Random Access Memory (RAM) 820, a Read
Only Memory (ROM) 830, a memory device 840, and an Input Output
("I/O") interface 850. The elements of the processing circuitry 800
are communicatively coupled via a local interface 802. The elements
of the processing circuitry 800 described herein are not intended
to be limiting in nature, and the processing circuitry 800 can
include other elements.
In various embodiments, the processor 810 can comprise any
well-known general purpose arithmetic processor, programmable logic
device, state machine, or Application Specific Integrated Circuit
(ASIC), for example. The processor 810 can include one or more
circuits, one or more microprocessors, ASICs, dedicated hardware,
or any combination thereof. In certain aspects embodiments, the
processor 810 is configured to execute one or more software
modules. The processor 810 can further include memory configured to
store instructions and/or code to various functions, as further
described herein. In certain embodiments, the processor 810 can
comprise a general purpose, state machine, or ASIC processor, and
various processes can be implemented or executed by the general
purpose, state machine, or ASIC processor according software
execution, by firmware, or a combination of a software execution
and firmware.
The RAM and ROM 820 and 830 can comprise any well-known random
access and read only memory devices that store computer-readable
instructions to be executed by the processor 810. The memory device
840 stores computer-readable instructions thereon that, when
executed by the processor 810, direct the processor 810 to direct
the spectrophotometer 10 to perform various aspects of the
embodiments described herein.
As a non-limiting example group, the memory device 840 can comprise
one or more non-transitory devices or mediums including an optical
disc, a magnetic disc, a semiconductor memory (i.e., a
semiconductor, floating gate, or similar flash based memory), MLC
Negative-AND-based flash memory, a magnetic tape memory, a
removable memory, combinations thereof, or any other known memory
means for storing computer-readable instructions. The I/O interface
850 can comprise device input and output interfaces such as
keyboard, pointing device, display, communication, and/or other
interfaces, such as a network interface, for example. The local
interface 802 electrically and communicatively couples the
processor 810, the RAM 820, the ROM 830, the memory device 840, and
the I/O interface 850, so that data and instructions can be
communicated among them.
In certain aspects, the processor 810 is configured to retrieve
computer-readable instructions and data stored on the memory device
840, the RAM 820, the ROM 830, and/or other storage means, and copy
the computer-readable instructions to the RAM 820 or the ROM 830
for execution, for example. The processor 810 is further configured
to execute the computer-readable instructions to implement various
aspects and features of the embodiments described herein.
Although embodiments have been described herein in detail, the
descriptions are by way of example. The features of the embodiments
described herein are representative and, in alternative
embodiments, certain features and elements can be added or omitted.
Additionally, modifications to aspects of the embodiments described
herein can be made by those skilled in the art without departing
from the spirit and scope of the present invention defined in the
following claims, the scope of which are to be accorded the
broadest interpretation so as to encompass modifications and
equivalent structures.
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